Rock
'til you Drop: Starting and Stopping
Harmonic Rock and Roll (continued)
Car Rocking Symptoms
When inspecting a freight car, there are several telltale signs that the car
is a bad actor, with regard to harmonic rocking. The following components should
be visually and dimensionally checked:
•
Springs. Look for evidence that the springs are cracked or broken, or
that they have compressed "solid." Wear or shiny marks between the
spring coils (see Figure 3) are evidence of solid springs.
• Friction Wedges or Friction Castings. Inspect the wedges for excessive
rise above the top of bolster. On most Barber truck designs, wedge rise should
not exceed nominally 3/4 inches. For most Ride Control designs, the wedge rise
should not exceed nominally 1-3/4 inches. Also inspect the column wear plates
for excessive wear or hollowing of the plate.
•
Side Bearing Clearance and Wear Plates. Side bearing clearance should
not exceed 5/16 inches, or excessive rocking will be allowed. Inspect the body
wear plates for signs of cracking or excessive pounding. Sometimes the wear plates
will be severely dished or hollowed from the repetitive pounding into the roller
(see Figure 4).
• Centerplate Casting. The centerplate casting will show signs of cracking,
particularly around the fillet area or along the relief area on the bottom of
the centerplate.
Most rock and roll derailments are caused primarily by lack of damping in the
car, or excessive side bearing clearance. For track to be a primary cause, the
track structure must be severely deteriorated with a number of consecutive, staggered,
pumping joints. To prevent rock off derailments, avoid operating trains in the
critical speed range of 12 to 24 mph when handling loaded hopper cars over jointed
rail. Heeding these operating precautions, maintaining the track joints and insuring
proper damping in the car suspension can make harmonic rock and roll a thing
of the past.
SEPTEMBER 2004 "Truck Warp:
Causes and Cures (Part 1 of 2)" READ
ARTICLEOCTOBER 2004 "Truck Warp: Causes
and Cures (Part 2 of 2)" READ
ARTICLE
Register to receive free editorial updates and current information from
Interface Journal CLICK HERE
Copyright Interface Journal 2004 - 2008
This
content
may not be reproduced without written permission. All
tradenames and logos are protected under copyright law and are
the property of their respective owners. | Read our
privacy/legal statement before utilizing this site.
•
Springs. Look for evidence that the springs are cracked or broken, or
that they have compressed "solid." Wear or shiny marks between the
spring coils (see Figure 3) are evidence of solid springs.
•
Side Bearing Clearance and Wear Plates. Side bearing clearance should
not exceed 5/16 inches, or excessive rocking will be allowed. Inspect the body
wear plates for signs of cracking or excessive pounding. Sometimes the wear plates
will be severely dished or hollowed from the repetitive pounding into the roller
(see Figure 4).
